Sheridan Douglas L, Kong Yong, Parker Sirlester A, Dalby Kevin N, Turk Benjamin E
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
J Biol Chem. 2008 Jul 11;283(28):19511-20. doi: 10.1074/jbc.M801074200. Epub 2008 May 15.
Mitogen-activated protein kinases (MAPKs) mediate cellular responses to a wide variety of extracellular stimuli. MAPK signal transduction cascades are tightly regulated, and individual MAPKs display exquisite specificity in recognition of their target substrates. All MAPK family members share a common phosphorylation site motif, raising questions as to how substrate specificity is achieved. Here we describe a peptide library screen to identify sequence requirements of the DEF site (docking site for ERK FXF), a docking motif separate from the phosphorylation site. We show that MAPK isoforms recognize DEF sites with unique sequences and identify two key residues on the MAPK that largely dictate sequence specificity. Based on these observations and computational docking studies, we propose a revised model for MAPK interaction with substrates containing DEF sites. Variations in DEF site sequence requirements provide one possible mechanism for encoding complex target specificity among MAPK isoforms.
丝裂原活化蛋白激酶（MAPKs）介导细胞对多种细胞外刺激的反应。MAPK信号转导级联受到严格调控，并且单个MAPKs在识别其靶底物时表现出极高的特异性。所有MAPK家族成员都共享一个共同的磷酸化位点基序，这就引发了关于如何实现底物特异性的问题。在这里，我们描述了一个肽库筛选，以确定DEF位点（ERK FXF的对接位点）的序列要求，DEF位点是一个与磷酸化位点分开的对接基序。我们表明，MAPK亚型识别具有独特序列的DEF位点，并确定了MAPK上的两个关键残基，它们在很大程度上决定了序列特异性。基于这些观察结果和计算对接研究，我们提出了一个修订后的模型，用于MAPK与含有DEF位点的底物的相互作用。DEF位点序列要求的变化为编码MAPK亚型之间复杂的靶标特异性提供了一种可能的机制。
